That's fairly subjective. White tires look great if all you do is take pics of your bike to post on the internet and never ride the thing. Isn't that what fixed-gears are for?

Actually, I ride on a daily basis and was actually just marvelling the other day over how clean my white tires stay. I've found that even when the tread does get a little sh*tty looking, all it takes is riding over a patch of fresh cement and it tends to clean them up.

As far as Fyxations go, a friend of mine has them and they don't seem too bad if colors are your sort of thing. They're just as tough than a lot of tires in their price bracket and I'm assuming your not planning on competing in triathalons with them. The green ones look amazing in real life.

Oops...forgot where I was. Get black. Only the black ones contain carbon. Actually...they're all terrible. Forget they exist.